SEPARATING WALLS (NEW BUILDINGS) SOUNDPROOFING

Diagram 2-20: Wall type 2.3 and 2.4 – external cavity wall with masonry inner leaf – stagger

Diagram 2-21: Wall type 2 – tied junction – external cavity wall with internal masonry wall

Junctions with an external cavity wall with timber frame inner leaf

2.77 Where the external wall is a cavity wall:

1. the outer leaf of the wall may be of any construction, and
2. the cavity should be stopped with a flexible closer. See Diagram 2-22.

2.78 Where the inner leaf of an external cavity wall is of framed construction, the framed inner leaf should:

1. abut the separating wall, and
2. be tied to it with ties at no more than 300 mm centres vertically.

The wall finish of the inner leaf of the external wall should be:

1. one layer of plasterboard, or
2. two layers of plasterboard where there is a separating floor
3. each sheet of plasterboard to be of minimum mass per unit area 10 kg/m², and
4. all joints should be sealed with tape or caulked with sealant.

Diagram 2-22: Wall type 2 – external cavity wall with timber frame inner leaf

Junctions with an external solid masonry wall

2.79 No guidance available (seek specialist advice).

Junctions with internal framed walls

2.80 There are no restrictions on internal framed walls meeting a type 2 separating wall.

Junctions with internal masonry walls

2.81 Internal masonry walls that abut a type 2 separating wall should have a mass per unit area of at least 120 kg/m² excluding finish.

2.82 Where there is a separating floor, internal masonry walls should have a mass per unit area of at least 120 kg/m² excluding finish.

2.83 When there is no separating floor with separating wall type 2.3 or 2.4 there is no minimum mass per unit area for internal masonry walls.

Resistance to the passage of sound 27